Founded in Providence, Rhode Island, the Screw Machine Products Company originally specialized in manufacturing precision turned-metal parts. In 1918, the company diversified into the booming telecommunications industry by inventing and patenting the Select-O-Phone, a private, internal office switchboard and intercom system that allowed businesses to communicate between departments without using the public telephone network. Over the next three decades, the company successfully manufactured and marketed the Select-O-Phone and its compact counterpart, the Select-O-Phone Junior, tailoring their private branch systems to offices, factories, and schools. Recognizing the value of this established internal communication niche, the Kellogg Switchboard & Supply Company bought the firm in March 1948, integrating the Rhode Island company's designs into its own massive catalog and continuing production of the Select-O-Phone line well into the mid-1960s.
